Allograft outcomes in outbred mice.

Inbreeding depression and lack of genetic diversity in inbred mice could mask unappreciated causes of graft failure or remove barriers to tolerance induction. To test these possibilities, we performed heart transplantation between outbred or inbred mice. Unlike untreated inbred mice in which all allografts were rejected acutely (6-16 days posttransplantation), untreated outbred mice had heterogeneous outcomes, with grafts failing early (<4 days posttransplantation), acutely (6-24 days) or undergoing chronic rejection (>75 days). Blocking T cell costimulation induced long-term graft acceptance in both inbred and outbred mice, but did not prevent the early graft failure observed in the latter. Further investigation of this early phenotype established that it is dependent on the donor, and not the recipient, being outbred and that it is characterized by hemorrhagic necrosis and neutrophilic vasculitis in the graft without preformed, high titer antidonor antibodies in the recipient. Complement or neutrophil depletion prevented early failure of outbred grafts, whereas transplanting CD73-deficient inbred hearts, which are highly susceptible to ischemia-reperfusion injury, recapitulated the early phenotype. Therefore, outbred mice could provide broader insight into donor and recipient determinants of allograft outcomes but their hybrid vigor and genetic diversity do not constitute a uniform barrier to tolerance induction.

Modeling community asbestos exposure near a vermiculite processing facility: Impact of human activities on cumulative exposure.

Contaminated vermiculite ore from Libby, Montana was processed in northeast Minneapolis from 1936 to 1989 in a densely populated urban residential neighborhood, resulting in non-occupational exposure scenarios from plant stack and fugitive emissions as well as from activity-based scenarios associated with use of the waste rock in the surrounding community. The objective of this analysis was to estimate potential cumulative asbestos exposure for all non-occupationally exposed members of this community. Questionnaire data from a neighborhood-exposure assessment ascertained frequency of potential contact with vermiculite processing waste. Monte Carlo simulation was used to develop exposure estimates based on activity-based concentration estimates and contact durations for four scenarios: S1, moved asbestos-contaminated waste; S2, used waste at home, on lawn or garden; S3, installed/removed vermiculite insulation; S4, played in or around waste piles at the plant. The simulation outputs were combined with air-dispersion model results to provide total cumulative asbestos exposure estimates for the cohort. Fiber emissions from the plant were the largest source of exposure for the majority of the cohort, with geometric mean cumulative exposures of 0.02 fibers/cc × month. The addition of S1, S2 and S3 did not significantly increase total cumulative exposure above background exposure estimates obtained from dispersion modeling. Activity-based exposures were a substantial contributor to the upper end of the exposure distribution: 90th percentile S4 exposure estimates are ∼10 times higher than exposures from plant emissions. Pile playing is the strongest source of asbestos exposure in this cohort, with other activity scenarios contributing less than from plant emissions.

The confounding effect of response amplitude on MVPA performance measures.

Multi-voxel pattern analysis (MVPA) is proving very powerful in the analysis of fMRI timeseries data, yielding surprising sensitivity, in many different contexts, to the response characteristics of neurons in a given brain region. However, MVPA yields a metric (classification performance) that does not readily lend itself to quantitative comparisons across experimental conditions, brain regions or people. This is because performance is influenced by a number of factors other than the sensitivity of neurons to the experimental manipulation. One such factor that varies widely but has been largely ignored in MVPA studies is the amplitude of the response being decoded. In a noisy system, it is expected that measured classification performance will decline with declining response amplitude, even if the underlying neuronal specificity is constant. We document the relationship between response amplitude and classification performance in the context of orientation decoding in the visual cortex. Flickering sine gratings were presented at each of two orthogonal orientations in a block design (multivariate experiment) or an event-related design (univariate experiment). Response amplitude was manipulated by varying stimulus contrast. Orientation classification performance in retinotopically defined occipital area V1 increased approximately linearly with the logarithm of stimulus contrast. As expected, univariate response amplitude also increased with contrast. Similar results were obtained in V2, V3 and V3A. Plotting classification performance against response amplitude gave a function with a compressive non-linearity that was well fit by a power function. Knowledge of this function potentially allows adjustment of classification performance to take account of the effect of response size, making comparisons across brain areas, categories or people more meaningful.

Teamwork behaviours and errors during neonatal resuscitation.

OBJECTIVE: To describe relationships between teamwork behaviours and errors during neonatal resuscitation. METHODS: Trained observers viewed video recordings of neonatal resuscitations (n = 12) for the occurrence of teamwork behaviours and errors. Teamwork state behaviours (such as vigilance and workload management, which extend for some duration) were assessed as the percentage of each resuscitation that the behaviour was observed and correlated with the percentage of observed errors. Teamwork event behaviours (such as information sharing, inquiry and assertion, which occur at specific times) were counted in 20-s intervals before and after resuscitation steps, and a generalised linear mixed model was calculated to evaluate relationships between these behaviours and errors. RESULTS: Resuscitation teams who were more vigilant committed fewer errors (Spearman's rho for vigilance and errors = -0.62, 95% CI -0.07 to -0.87, p = 0.031). Assertions were more likely to occur before errors than correct steps (OR = 1.44, 95% CI 1.10 to 1.89, p = 0.008) and teaching/advising occurred less frequently after errors (OR = 0.59, 95% CI 0.37 to 0.94, p = 0.028). Though not statistically significant, there was less information sharing before errors (OR = 0.90, 95% CI 0.77 to 1.05, p = 0.172). CONCLUSIONS: Vigilance is an important behaviour for error management. Assertion may have caused errors, or perhaps was an indicator for some other factor that caused errors. Teams may have preferred to resolve errors directly, rather than using errors as opportunities to teach their teammates. These observations raise important questions about the appropriate use of some teamwork behaviours and how to include them in team training programmes.

Type I interferons are not critical for skin allograft rejection or the generation of donor-specific CD8+ memory T cells.

Type I interferons (IFN-I) link innate to adaptive immunity in microbial infection, autoimmune disease and tumor immunity. It is not known whether IFN-I have an equally central role in alloimmunity. Here we tested this possibility by studying skin allograft survival and donor-specific CD8+ T-cell responses in mice that lack the IFN-I receptor (IFN-IR-/-). We found that IFN-IR-/- mice reject fully allogeneic wild-type skin grafts at the same rate as wild-type recipients. Similarly, allograft rejection was not delayed if IFN-IR-/- male skin was transplanted to syngeneic IFN-IR-/- female mice. Quantitation of the male (H-Y)-specific CD8+ T-cell response in these mice revealed normal generation of donor-specific CD8+ effector T cells but fourfold reduction in CD8+ memory T cells. Memory CD8+ T cells generated in the absence of IFN-IR had normal phenotype and recall function, assessed by ex vivo cytokine production and the ability of IFN-IR-/- mice to mount second set rejection. Finally, these memory T cells were maintained at a constant number despite their inability to respond to IFN-1. Our findings indicate that IFN-I cytokines are not critical for acute allograft rejection or for the expansion and differentiation of donor-specific CD8+ T cells into long-lived, functional memory T cells.

A randomized clinical trial evaluating silicone earplugs for very low birth weight newborns in intensive care.

OBJECTIVE: To determine whether very low birth weight (VLBW) newborns (<1500 g) wearing silicone earplugs grow larger and perform better on developmental exams than controls. STUDY DESIGN: VLBW newborns (n=34) were randomized to wearing earplugs or not. Hospital outcomes were abstracted from medical charts by research staff masked to intervention status. Fourteen extremely low birth weight (ELBW) newborns (<1000 g) were also evaluated at 18 to 22 months. RESULT: After adjusting for birth weight, 11 surviving newborns in the earplug group were 225 g (95% CI: 45, 405) heavier at 34 weeks post menstrual age than the 13 controls. Six ELBW earplug infants scored 15.53 points (95% CI: 3.03, 28.02) higher than six controls on the Bayley Mental Development Index. Their head circumferences were 2.59 cm (95% CI: 0.97, 4.21) larger. CONCLUSION: Earplugs may facilitate weight gain in VLBW newborns. Better outcomes may persist at 18 to 22 months at least in ELBW infants.

Teaching teamwork during the Neonatal Resuscitation Program: a randomized trial.

OBJECTIVE: To add a team training and human error curriculum to the Neonatal Resuscitation Program (NRP) and measure its effect on teamwork. We hypothesized that teams that received the new course would exhibit more teamwork behaviors than those in the standard NRP course. STUDY DESIGN: Interns were randomized to receive NRP with team training or standard NRP, then video recorded when they performed simulated resuscitations at the end of the day-long course. Outcomes were assessed by observers blinded to study arm allocation and included the frequency or duration of six team behaviors: inquiry, information sharing, assertion, evaluation of plans, workload management and vigilance. RESULT: The interns in the NRP with team training group exhibited more frequent team behaviors (number of episodes per minute (95% CI)) than interns in the control group: information sharing 1.06 (0.24, 1.17) vs 0.13 (0.00, 0.43); inquiry 0.35 (0.11, 0.42) vs 0.09 (0.00, 0.10); assertion 1.80 (1.21, 2.25) vs 0.64 (0.26, 0.91); and any team behavior 3.34 (2.26, 4.11) vs 1.03 (0.48, 1.30) (P-values <0.008 for all comparisons). Vigilance and workload management were practiced throughout the entire simulated code by nearly all the teams in the NRP with team training group (100% for vigilance and 88% for workload management) vs only 53 and 20% of the teams in the standard NRP. No difference was detected in the frequency of evaluation of plans. CONCLUSION: Compared with the standard NRP, NRP with a teamwork and human error curriculum led interns to exhibit more team behaviors during simulated resuscitations.

Effect of Cnidoscolus aconitifolius leaf extract on the blood glucose and insulin levels of inbred type 2 diabetic mice.

The effects of Cnidoscolus aconitifolius (CA) leaf extract and chlorpropamide on blood glucose and insulin levels in the inbred type 2 diabetic mice are reported. After treatment with CA, the glucose levels were measured at 0 and 2-hour intervals in experimental groups and controls. Group I received no treatment and served as control; Group II was the reference and it received chlorpropamide; Groups I-III were moderately diabetic, 100-300 mg/dL blood glucose levels while Group IV were severely diabetic (> 300 mg/dL). Groups III and IV received CA and served as test groups. There was no significant difference between the blood glucose levels at 0 and 2 hours for the control group, (P>0.23) but there were statistically significant differences for Group II (P<0.0002); Group III (P<0.002) and Group IV (P<0.0001). For moderately diabetic mice, CA and chlorpropamide decreased the glucose levels by 25.6% and 16.3% respectively while for the severely diabetic mice CA decreased the blood glucose by 43.7%. It is proposed that CA has an insulinogenic property that possibly stimulated dormant beta-cells to secrete insulin. The histopathology of several organs in the treated animals was found to differ from the expected. The islets of Langerhans for example were found to be preserved in the time frame examined. Also the liver and kidney were found to display milder pathology in the treated groups.

Mathematical models for conventional and microwave thermal deactivation of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli.

Temperature dependencies of survival fecal coliforms such as Enterococcus faecalis, Staphylococcus aureus and Escherichia coli in water were investigated between 25-65 degrees C. Measured dependencies had "bell" shaped form with maximum bacterial viability at 35-45 degrees C. The rates of growth and decay of bacterial viability depend on specific forms of bacteria. At temperatures of 60-65 degrees C the number of viable bacteria decreased in one hundred times in comparison with the maximum value. Similar "bell" shape forms were found for dependencies between bacterial viability and time of microwave (dielectric) heating of water. The dependencies had maximum value at 1-2 min of microwave heating. Then, the number of viable bacteria decreased, and at 4-5 min of microwave heating, became insignificantly small. The proposed mathematical models for conventional and microwave heating took into account "growth" and "death" factors of bacteria, and had forms of second degree polynomial functions. The results showed good relationships (with coefficient correlation 0.84-0.99) between the proposed mathematical models and experimental data for both conventional and microwave heating.

Mathematical model of manganese ion catalyzed microwave deactivation of Enterococcus faecalis, Staphylococcus aureus and Escherichia coli.

Enterococcus faecalis, Staphylococcus aureus and Escherichia coli survival was investigated using microwave irradiation (power 130 W) both in a water control and in the presence of a 1 microM manganese ion solution. Measured survival dependencies had "bell" shape form with maximum bacterial viability between 1-2 min of microwave heating. Additional heating revealed bacteria survival decreasing up to 3 min of microwave heating when viability became insignificantly small. The total deactivation time of bacteria in the presence of manganese ions was significantly smaller then that of bacteria irradiated in the microwave without manganese ions present (4-5 min). One possible explanation for the rapid reduction of bacterial survival during microwave irradiation in the presence of manganese ions is that increasing manganese ion penetration into bacteria along with microwave irradiation related to an increase of kinetic energy of ions, and damaging of bacteria by metal ions. The proposed mathematical model for microwave heating took into account "growth" and "death" factors of bacteria. It assumes that rates of bacterial growth and decay are linear functions of water temperature, and rate of bacterial decay that relates with metal concentration into water is also linear, which influenced the differential equation for the dependence between number of survival bacteria and temperature water. By using proportionality between the time of microwave heating and water temperature we derived the differential equation, between bacterial viability and time of microwave irradiation which was used as mathematical model for microwave heating in the presence of metal ions. This model had forms of second-degree polynomial functions. We received good relationships (with coefficient of correlation 0.92-0.99) between proposed mathematical model and experimental data for all bacterial deactivation.

In vitro reconstitution of legumin (11S) mRNA and binding proteins as related to post-transcriptional regulation of protein synthesis in developing alfalfa embryos.

There is undetectable transcription of 11S storage protein (medicagin) mRNA by nuclei isolated from pre-cotyledonary-stage somatic embryos of alfalfa (Medicago sativa L). However, this message exists at steady-state levels in the embryos at this stage of development without concomitant synthesis of the storage protein. At the pre-cotyledonary stage, therefore, the transcriptional rate for 11S mRNA is low; what message is transcribed is sequestered in the form of mRNP complexes and is not recruited into polysomes in vivo (33). Both transcription (in vivo and in isolated nuclei) and translation of the 11S mRNA are evident at the onset of cotyledon development in somatic and zygotic embryos, reaching a maximum during expansion of the cotyledons and then declining as the embryos mature. Pre-cotyledonary-stage somatic embryos which do not utilize the 11S-mRNA in polysomes lack certain mRNA-binding proteins (32, 36 and 38 kD) which are present at later stages of development. These mRNA-binding proteins may be responsible for the initiation of large polysome formation since they were exclusively present in the translational extracts of cotyledonary somatic and zygotic embryos in which there was no repression of storage protein synthesis. In contrast, the pre-cotyledonary somatic embryos contained a different set of 11S-mRNA-binding proteins (28, 50, 55, and 62 kD) whose presence in the cotyledonary stage embryos was very rare or non-existent; these could be responsible for preventing translation.

Sensitivity to optic flow in human cortical areas MT and MST.

The macaque V5/MT complex comprises several sub-regions but little is known of their human homologues. We examined human V5/MT with fMRI in terms of specificity to optic flow stimuli, a key characteristic of macaque MST. Stimuli were large fields of moving dots, forming coherent global flow patterns. Random motion was used as a control. Retinotopic mapping was also conducted. The previously suggested existence of at least two distinct sub-regions, MT and MST, within the V5/MT complex was confirmed. Human MT is activated about equally by all moving dot patterns, including random motion, suggesting that it has little sensitivity to global flow structure. As previously described, this region shows strong signs of retinotopic organization and is only weakly activated by stimuli confined to the ipsilateral hemifield. In human MST, located immediately anterior to MT and strongly driven by ipsilateral stimuli, activation varies markedly with optic flow structure. The strongest activation is produced by complex flow that contains multiple flow components (expansion, contraction and rotation). Single components produce rather less response, while rigid translation and random motion produce less still. The results suggest that human MST is strongly specialized for encoding global flow properties, while human MT is less so.

Endogenous protein kinase-C activity and phosphorylated proteins in messenger ribonucleoprotein complexes of developing embryos of alfalfa.

Developing somatic and zygotic embryos of alfalfa (Medicago sativa L.) exhibited endogenous protein kinase activity and protein acceptors of phosphate groups using both cell-free translational extracts and oligo(dT)-cellulose-column-purified mRNPs. The cell-free-translation extracts from pre-cotyledonary-stage somatic embryos had approximately 50- and 100-fold more protein kinase activity than cotyledonary-stage somatic and zygotic embryos. Several polypeptides were phosphorylated; some of them were unique to the early stage and some to the late-stage developing embryos. A 65 kDa protein was phosphorylated heavily in pre-cotyledonary-stage somatic embryos. This phosphorylated protein was comprised of three main components, two of which were phosphorylated heavily. Heat-shock treated-embryos lost their exitant kinase activity and at the same time another form of protein kinase activity was activated which phosphorylated a novel 28 kDa protein. Endogenous protein kinase activity was also observed within the mRNPs of polysomal and non-polysomal fractions of developing embryos, and this phosphorylated only 65, 43 and 30 kDa proteins within these fractions. A 30 kDa protein from the pre-cotyledonary-stage somatic embryos showed a higher affinity for accepting phosphate groups than the proteins from cotyledonary-stage somatic or zygotic embryos. The activity of protein kinase was largely c-AMP-independent, but was dependent on Ca2+, phospholipid and phorbol ester. The enzyme belongs to the protein kinase-C family; the 65 kDa protein cross-reacts with antibodies made against protein kinase-C (alpha- and beta-isoforms) and it may be an autophosphorylated protein.

Systemic infection, interleukin 1beta, and cognitive decline in Alzheimer's disease.

Activated microglia, the resident macrophages of the brain, are a feature of Alzheimer's disease. Animal models suggest that when activated microglia are further activated by a subsequent systemic infection this results in significantly raised levels of interleukin 1beta within the CNS, which may in turn potentiate neurodegeneration. This prospective pilot study in Alzheimer's disease subjects showed that cognitive function can be impaired for at least two months after the resolution of a systemic infection and that cognitive impairment is preceded by raised serum levels of interleukin 1beta. These relations were not confounded by the presence of any subsequent systemic infection or by baseline cognitive scores. Further research is needed to determine whether recurrent systemic infections drive cognitive decline in Alzheimer's disease subjects through a cytokine mediated pathway.

Conformation of the hexasaccharide repeating subunit from the Vibrio cholerae O139 capsular polysaccharide.

In the past decade, several outbreaks of cholera have been reported to be caused by Vibrio cholerae O139, a strain which differs from the more common O1 strain in that the former is encapsulated. The hexasaccharide repeating subunit has been isolated from the V. cholerae O139 capsular polysaccharide by digestion with a recently discovered polysaccharide lyase derived from a bacteriophage specific for this serogroup. It specifically cleaves at a single position of the 4-linked galacturonic acid producing an unsaturated sugar product in quantities for conformational studies by (1)H and (13)C NMR spectroscopy. We report conformational studies on this oligosaccharide by molecular modeling and NMR spectroscopy including nuclear Overhauser effects and residual dipolar coupling of a sample weakly oriented in liquid crystalline solution. The structure contains a tetrasaccharide epitope homologous to the human Lewis(b) blood group antigen, which adopts a relatively well-defined single conformation. Comparison of these results with those of a previously published study of the intact capsular polysaccharide indicates that the conformations of the epitope in the two cases are identical or at least closely similar. Thus, this epitope, which may be essential for the pathogenicity of this V. cholerae strain, is not a "conformational epitope" requiring a certain critical size for antigenicity as has been reported for several other bacterial capsular antigens.

Estimating receptive field size from fMRI data in human striate and extrastriate visual cortex.

Functional magnetic resonance imaging (fMRI) was used to estimate the average receptive field sizes of neurons in each of several striate and extrastriate visual areas of the human cerebral cortex. The boundaries of the visual areas were determined by retinotopic mapping procedures and were visualized on flattened representations of the occipital cortex. Estimates of receptive field size were derived from the temporal duration of the functional activation at each cortical location as a visual stimulus passed through the receptive fields represented at that location. Receptive fields are smallest in the primary visual cortex (V1). They are larger in V2, larger again in V3/VP and largest of all in areas V3A and V4. In all these areas, receptive fields increase in size with increasing stimulus eccentricity. The results are qualitatively in line with those obtained by others in macaque monkeys using neurophysiological methods.

Model studies toward the total synthesis of the Lycopodium alkaloid spirolucidine.

[reaction: see text] A strategy for the synthesis of the spirocyclic core of spirolucidine was explored through a model study. The diene 4a was prepared and photolyzed to give the desired [2 + 2] photoadduct 17 containing the correct relative stereochemistry corresponding to spirolucidine.

Evidence of a critical leucite particle size for microcracking in dental porcelains.

The leucite particles in dental porcelains are often partially encircled by microcracks that are the result of the thermal expansion mismatch between leucite and the surrounding glass matrix. Although the magnitude of the stress at the particle-matrix interface is independent of the particle size (Selsing, 1961), Davidge and Green (1968) showed experimentally that there is a critical particle size below which microcracking is absent. The critical particle size is explained by a Griffith-type energy balance criterion: Below the critical size, the stress magnitude may be sufficient to cause cracking, but there is insufficient strain energy for the creation of the new surfaces of the microcrack. The purpose of the present study was to determine whether the mean leucite particle size of a dental porcelain influences the degree of microcracking in the porcelain. Microcrack density, leucite particle surface area per unit volume, and leucite mean volume-surface diameter, D3,2, were determined by quantitative stereology on 10 specimens each of 6 dental porcelains and Component No. 1 of the Weinstein et al. patent (US Patent 3,052,982, 1962). The fraction of leucite particles with microcracks around them, f(mc), was estimated for each porcelain from the microcrack density and the leucite surface area. Using the equations of Selsing (1961) and Davidge and Green (1968), we calculated the critical particle diameter, Dc, for leucite to be 4 microm. The porcelains were partitioned according to whether their mean leucite particle diameters, D3,2, fell above or below Dc, and their values of f(mc) were analyzed by a permutation test with random re-sampling. The porcelains with mean leucite particle diameters below Dc had a significantly lower fraction of cracked particles compared with the porcelains with mean leucite particle diameters above Dc (p < 0.05). This study provides evidence that microcracking in dental porcelain can be minimized by a reduction of the mean leucite particle diameter to less than 4 microm.

Comparison of 2-octyl cyanoacrylate adhesive, fibrin glue, and suturing for wound closure in the porcine urinary tract.

OBJECTIVES: To evaluate 2-octyl cyanoacrylate glue (OCG) for wound closure in the urinary tract and compare the ability of OCG, fibrin glue (FG), and suture to withstand physiologic and supraphysiologic stress, because the use of tissue adhesives such as OCG or FG might simplify laparoscopic surgery. METHODS: Female domestic pigs (n = 22) underwent a 7.5-cm cystotomy. Of these, 8 had closure with OCG and 8 with FG (6 open and 2 laparoscopic in each group). The controls were closed with suture (n = 4) or not at all (n = 2). Postoperative catheter drainage was not used. At 2 days or 4 weeks postoperatively, the bladders were filled with saline to 200 mm Hg pressure and the cystotomy scars inspected for leakage. The excised scars were also examined histologically. RESULTS: The 2 OCG and 2 FG pigs tested on postoperative day 2 leaked at less than 200 mm Hg. None of the 6 OCG pigs tested at 4 weeks leaked at less than 200 mm Hg, including the 2 closed laparoscopically. Of the 6 FG pigs intended for study at 4 weeks, 3 (including the 2 closed laparoscopically) died from a massive urine leak, 1 tested at 4 weeks leaked, and 2 did not leak. Thus, 4 of 6 FG pigs leaked by 4 weeks compared with none in the OCG group (P = 0.06). The histologic examination was similar in the two groups. CONCLUSIONS: Preliminary results suggest that OCG provides enough strength to hold together a large bladder wound. In the same model, FG did not consistently provide adequate closure.